The purpose of this project is the study of Aleutian disease of mink, a persistent infection by the nondefective parvovirus, Aleutian disease virus (ADV). Peptide mapping of the ADV proteins demonstrate that p85 and p75 (the two capsid proteins) have extensive peptide homology but that the nonvirion p71 is not related to the two virion proteins. This is the first demonstration in parvoviruses of a virus-induced non-virion protein. Viral expression in permissive (feline) and nonpermissive (mink) cells has been compared and the results indicated that all three proteins (p85, p75 and p71) were expressed in both cell types, although no infectious virus production in mink cells was demonstrable. This system is under further study to determine at what level virus production is blocked in nonpermissive cells.